Thank you for the thoughtful feedback. I agree that ambiguity is the main issue any proposal like this has to handle carefully.

To clarify the design: TZUR display wordlists are not meant to replace or reinterpret existing BIP39 wordlists. They are separate, index-parallel display wordlists whose purpose is to render and accept a user-facing mnemonic in another language while keeping the canonical English BIP39 mnemonic as the seed of record.

localized TZUR display words → word indices → canonical English BIP39 words → standard BIP39 checksum validation → standard PBKDF2 → standard BIP32/BIP84 derivation

The localized words themselves are never passed directly into PBKDF2. Only the canonical English mnemonic is.

Your French example is exactly the edge case that needs to be explicit. A legacy French BIP39 mnemonic and a TZUR French display mnemonic are not the same thing. They are two different encodings that may use the same human language, and they must not be silently treated as interchangeable.

For that reason, a wallet implementing this convention should not just see “French words” and guess. It should know, or ask, which wordlist mode is being used:

The reference design also includes stable wordlist identifiers: language code, version, and SHA256 of the exact wordlist file. A wallet can persist that metadata alongside the wallet, and use it during restore to avoid ambiguity. But for maximum portability, the wallet should always show the canonical English mnemonic as the universal recovery form.

So I think your concern is valid. The safe rule is: never auto-detect between legacy non-English BIP39 and TZUR display lists when both exist. Make the mode explicit, keep the English mnemonic available, and treat the display mnemonic as a UX layer rather than a new seed derivation scheme.

On Saturday, June 13, 2026 at 7:36:05 PM UTC+3 conduition wrote:

Hey Daniel,

So basically this would allow a user to translate an english language BIP39 seed phrase to/from other languages, insured by the knowledge that it be converted back if needed for compatibility with english-only BIP39 wallets.

Neat idea. This is how BIP39 should've been done originally. Today, a BIP39 seed derives a different master key depending on what language is used to encode the source entropy, which was arguably a mistake because it breaks compatibility between implementations written for different locales, and incentivizes everyone to use seeds of the same language so that they're maximally compatible (which is exactly what happened).

I worry your proposal here might cause confusion if introduced today though. Say you are given a french language 12-word seed phrase. Do you map the word indices to english and then run PBKDF2 with your algorithm? Or do you run PBKDF2 on the french version as specified in the original BIP39?

There would need to be a clear way for humans and software to distinguish between a "locale-mapped seed phrase" using your spec, and a legacy french BIP39 seed phrase, so they know how to derive the correct master key.

I guess one could argue that non-english BIP39 seeds are so uncommon that you could safely assume the former, but still it leaves open an unfortunate ambiguity which could lead to lost funds in some cases.

What do you think of this?

regards,
conduition
On Saturday, June 13th, 2026 at 12:04 PM, Daniel Osemberg <danios...@gmail.com> wrote:

Hi list,
I would like to ask for early feedback on an idea before attempting any formal BIP submission.
The proposal is a display/input layer for BIP39 recovery phrases in additional native languages.
The important constraint is that this does not change the BIP39 cryptographic flow. The canonical mnemonic remains the existing BIP39 English wordlist, and PBKDF2 is still performed on the canonical English form.
The native-language lists are index-paired to the English BIP39 wordlist. In other words, each native word maps to the same 0-2047 index as the corresponding English BIP39 word. Wallets could display or accept the native-language form for UX purposes, but internally normalize back to the canonical English mnemonic before seed generation.
Motivation:
Many users around the world are asked to back up and restore Bitcoin wallets using English recovery words, even when English is not their native language. This creates UX risk, spelling mistakes, misunderstanding, and lower confidence during backup and recovery.
This proposal tries to improve multilingual recovery UX while keeping compatibility with existing BIP39 behavior.
This is not:
A new seed scheme
A replacement for BIP39
A new cryptographic standard
A change to PBKDF2 input
A wallet-specific format
It is intended as a display/input convention for wallets that want to support native-language recovery UX while preserving canonical BIP39 compatibility.
A draft implementation and wordlists are here:
https://github.com/osem23/bip39-wordlists-tzur
I would appreciate feedback on:
Whether this idea is appropriate for the BIP process at all
Whether it should be considered informational rather than standards-track
Whether the index-paired approach creates hidden risks
Whether wallet developers see practical value in this
How native-speaker review and normalization rules should be handled
Whether there is prior work I should study before continuing
Thank you,
Daniel

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